The use of cellular communications devices (often referred to as user equipment (UE)), including devices of varying capabilities from basic wireless telephony (often referred to as wireless or cellular telephones) to advanced capabilities including computing, personal digital assistant (PDA), data communication, etc. in addition to wireless telephony (often referred to as smartphones), has become nearly ubiquitous. Many such UEs include multiple radio interfaces, such as a cellular network radio interface for facilitating wireless telephony communications and an Internet protocol (IP) network interface for facilitating wireless data communications.
Although perhaps not originally developed for providing voice communication, UE IP network interfaces are commonly utilized for providing voice calls (often referred to as voice over IP (VoIP) calls). For example, alternative calling applications may be installed on a smartphone configuration of a UE to provide an IP call interface whereby the user of the UE may initiate and/or answer calls using an IP network, when available, in a manner similar to a traditional cellular call interface. Instead of the UE wireless leg of the call being placed over the cellular wireless network, the call is placed over the wireless IP network, such as using a WiFi wireless local area network (WLAN) link established by the UE IP network radio interface. The VoIP call, although utilizing a wireless IP link, will be routed via the IP network to the core telecommunications network using a gateway coupling the core telecommunications and IP networks, and thus is operable to terminate the call with various termination points in the telephony network. Such VoIP calling applications may be particularly desirable for providing calling services without incurring over-the-air charges often associated with cellular calls, to avoid long distance or international calling charges for the call, etc.
There are, however, a number of differences with respect to the implementation and use of such VoIP calling. For example, the operating system of the UEs is typically configured to prevent redirection of calls placed to certain emergency dispatch numbers from the cellular network to another network. Certain emergency dispatch numbers, such as 911, are generally specifically identified in some way, such as by being stored in a particular memory location (e.g., a register of the UE subscriber identity module (SIM) and/or within the native cellular calling application), and when any such number is dialed using the native cellular calling application the call is prevented from being intercepted or directed to a different interface by the operating system and/or the native calling application. Moreover, additional processing typically provided with respect to other telephone numbers, such as creation of a call log record for the call and preventing outbound dialing of the number when the UE is locked, is not performed with respect to the aforementioned identified emergency dispatch numbers.
The operation of the native calling application may be adapted to facilitate completing a call to the identified emergency dispatch number(s), such as by allowing outbound dialing of the identified emergency dispatch number when the UE is locked and/or using any cellular network available to the UE for initiating a call to an identified emergency dispatch number (i.e., not restricting the call to the use of a cellular network to which the user has subscribed). A call attempted to be placed to one of the aforementioned identified emergency dispatch numbers may nevertheless fail to complete. For example, there may be no cellular networks, whether one for which the user has subscribed or otherwise, and thus despite the native calling application searching for any cellular network none may be found. Similarly, the cellular coverage may be of such poor quality that although the native calling application may initially establish a call, the call may nevertheless be dropped before all or sufficient information regarding the emergency is communicated. However, even in situations where the UE IP network radio interface provides a reliable communication link, the operating system and/or native calling application operates to prevent the call to the identified emergency dispatch number from being intercepted and completed using the IP network.